A fuel cell system described in, for example, Patent Literature 1 is a conventional fuel cell system of a non anode-gas circulation type. The fuel cell system described in Patent Literature 1 includes a fuel cell stack formed by stacking multiple unit cells, and also includes a hydrogen tank, a supply shut-off valve and a pressure regulation valve as a supply system for an anode gas to the fuel cell stack. Moreover, the fuel cell system includes a storage tank (buffer tank) and an exhaust shut-off valve (purge valve) as an exhaust system for an anode off-gas from the fuel cell stack.
The above fuel cell system sets a first control state where the amount of supply of the anode gas to the fuel cell stack is small and a second control state where the amount of supply is large, and switches the first and second control states back and forth. In other words, the supply pressure of the anode gas is caused to pulsate. Thereby, the fuel cell system reduces the accumulation of impurities in some of the unit cells, and pumps and exhausts the anode off-gas to the storage tank.